The present invention is related to shafts for connecting separate camshaft sections or units into a single camshaft, and methods of their use in connecting camshaft sections or units together for use in an engine.
INGERSOLL-RAND engines of the KVR and KVT series currently use a camshaft which is constructed from separate cam sections which are connected together in a series by splined cam connecting shafts as shown and as designated herein as “prior art.” Each cam connecting shaft has splined ends upon each of which is matingly fitted a specific splined coupler.
The splined coupler is attached to the splined cam connecting shaft by a pair of retaining plates which seat into a groove behind the splines of the splined shaft. The splined coupler is then connected to the coupler end on the of the cam section via a plurality of bolts thereby connecting the cam section to the cam connecting shaft. The splines of the splined coupler fit into the gaps between the splines of the splined cam connecting shaft with sufficient clearance such that there is “play” (movement) between the splined coupler and the splines of the splined cam connecting shaft. The splined coupler is therefore not absolutely rigidly connected to or integral to the splined end of the splined cam connecting shaft.
Due to the “play” present in the coupling between the cam sections, wear of the splines of the splined coupler and the splines of the cam connecting shaft occurs during long term operation of the engine. Eventually, the “play” within the camshaft can increase to a magnitude which decreases the efficiency of the engine and decreases the stability and strength of the camshaft as a whole. This wear often necessitates replacement of the splined cam connecting shafts, and/or the replacement of the splined couplers which are mounted upon and which mate with the splines of the splined cam connecting shaft. Additionally, the grooves for the two retaining plates near the ends of the cam connecting shaft may introduce weakness in the shaft.
While the splined coupler has certain disadvantages as noted above, it advantageously enables the splined cam connecting shaft to be engineered in a more or less single standard configuration. Splined couplers designed to fit to cam sections having different coupling configurations can be fitted to the one type of splined connecting shaft. For example, the INGERSOLL-RAND KVR and KVT series has cam sections having couplers designated as “A,” “B,” “C,” and “D.” Each designation represents a different angle between the splines and the alignment pin. The alignment of the cam section is matched with the alignment of the splined coupler by an alignment pin which fits into an alignment hole on the cam section. Thus, splined couplings having different alignment pin positions can be attached to the same standard splined cam connecting shaft. Using various combinations of these four different couplers any of the at least ten different angles necessary can be created.